1. Field of the Invention
The present invention relates to an absorbent article such as elongated sanitary napkin suitable for nighttime use, disposable diaper, or urine absorbing pad to be worn inside an undergarment, diaper, etc. More particularly, the invention relates to an absorbent article with longitudinally extending leakage preventing walls disposed on right and left side portions of the skin-side surface.
2. Description of the Related Art
Sanitary napkins disclosed in Japanese Unexamined Patent Publication No. 2001-95842 (Patent Publication 1) and Japanese Unexamined Patent Publication No. 2002-656 (Patent Publication 2) are so elongated as to be suitable for nighttime use. This type of sanitary napkin is designed to be worn such that its front portion faces the vaginal opening being a menstrual blood excretory part while its intermediate and rear portions contact the perineum and the anus so that the rear portion faces the cleft of the buttocks. On the ski-side surface of the sanitary napkin, leakage preventing walls are provided to extend from the front portion to the rear portion on both right and left side portions of the sanitary napkin. These leakage preventing walls are allowed to rise from the skin-side surface over a long distance from adjacent a portion intended to face the vaginal opening to a portion intended to face the buttocks. With the leakage prevented walls present in a space between the skin-side surface of the sanitary napkin and the wearer's body, body liquid such as menstrual blood trying to flow down the perineum and the anus toward the posterior region during sleep may be blocked by the leakage preventing walls.
Japanese Unexamined Patent Publication No. S64-68503 (Patent Publication 3) discloses a disposable diaper, and Japanese Unexamined Patent Publication No. H04-12751 (Patent Publication 4) discloses a urine absorbing pad to be worn along with a diaper cover, undergarment or the like for absorption of urine.
Also in the disposable diaper and the urine absorbing pad, longitudinally extending leakage preventing walls are disposed on the skin-side surface at right and left side portions thereof. The disposable diaper and the urine absorbing pad are designed to be worn from the crotch to the buttocks, wherein the leakage preventing walls are allowed to rise toward the wearer's body from the crotch to the buttocks, coming into close contact with the wearer's body.
These absorbent articles disclosed in Patent Publications 1 to 4 are all elongated so as to be worn from the crotch to the buttocks. FIG. 14 is a sectional view of a conventional elongated absorbent article 100, diagrammatically showing how leakage preventing walls rise in a deformed article.
The absorbent article 100 has a main body 101 composed of a liquid-permeable topsheet, a liquid absorbent layer, and a liquid-impermeable backsheet. The main body 101 is intended to be worn such that its front end edge 101a is directed toward the lower abdomen while its rear end edge 101b is directed toward the buttocks. Leakage preventing walls 103 are fixed to the main body 101 at their front and rear ends 103a, 103b. The leakage preventing walls 103 exert an elastic contractive force to bring the front and rear ends 103a, 103b closer to each other, whereby the main body 101 is deformed with its skin-side surface being concavely curved. As a result, the leakage preventing walls 103 rise with their longitudinally extending tops 104 being moved away from the skin-side surface.
Since the leakage preventing walls 103 exert the elastic contractive force to bring the front and rear ends 103a, 103b closer to each other as set forth above, the tops 104 of the leakage preventing walls 103 try to extend linearly between the front and rear ends 103a, 103b. In the deformed state shown in FIG. 14, accordingly, the main body 101 subjected to the elastic contractive force is folded at a fold boundary 105 being a boundary between front and rear portions 101A, 101B, so that at the folding boundary 105, the tops 104 of the leakage preventing walls 103 are spaced as far away from the skin-side surface of the main body 101 as possible.
When the absorbent article 100 is worn, the front portion 101A faces the lower abdomen, the crotch and the perineum, while the rear portion 101B faces the anus and the cleft of the buttocks posterior to the anus, and optionally covers the region posterior to the cleft of the buttocks. Here, the tops 104 of the leakage preventing walls 103 will be relatively strongly pressed against the wearer's body at the folding boundary 105 and forward and rearward portions thereof, giving an uncomfortable feeling to the perineum, the anus and the buttocks.
At the folding boundary 105 where the tops 104 are farthest away from the main body 101, moreover, the leakage preventing walls 103 tend to be influenced by the body pressure from adjacent the anus or from the buttocks. Therefore, the leakage preventing walls 103 subjected to the body pressure tend to fall to the skin-side surface of the main body 101. As a result, the skin-side surface of the main body 101 will be widely covered with the leakage preventing walls 103 to reduce the substantial liquid absorbing area of the main body 101, which results in causing liquid to leak laterally or obliquely rearward.